Speaker
Description
Proton–nucleus collisions at the LHC provide a powerful laboratory to investigate initial-state phenomena in heavy-ion physics. Fluctuations in the proton configuration can significantly modify its effective interaction strength, biasing estimates of event activity and, consequently, the inferred number of wounded nucleons in the Pb nucleus. In this context, dijets offer a particularly sensitive probe, as they enable a precise characterization of the initial-state kinematics of the hard scattering. In this talk, we present recent ATLAS results studying the role of proton configurations in p+A collisions, using dijet events in p+Pb collisions at $\sqrt{s_{NN}}$=8.16 TeV collected in 2016. The results investigate correlations between event activity, forward neutron production, and the initial-state kinematics of the hard process, providing new evidence for the role of proton shape fluctuations in these collisions. These measurements provide the first quantitative input toward exploring the relationship between hard scattering processes and nuclear breakup. The data offer new opportunities to link proton spatial configurations, typically characterized via generalized parton distribution functions, with nuclear breakup and the overall interaction strength in p+A reactions, and provide useful insights to understand centrality biases affecting different geometry estimators in hard-scatterings.
| Is this an experimental talk? | Yes |
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| Is this on behalf of a collaboration? | Yes |
| Which collaboration? | ATLAS |
| Are you willing to present as a poster if it is not selected for oral presentation? | Yes |